Application of Fuzzy Control Base on Changeable Universe to Superheated Steam Temperature Control System

The cascade control systems are generally adopted in the units of power plants, same to the application showed in this paper. The main controller employs the FLC based on the changeable universe of discourse that is designed in the paper. According to the inputs of the main FLC, the paper introduces a fuzzy variable α to turn automatically the range of universe of discourse and simulates the man’s fuzzy control process from rough to exact control process. The improved fuzzy logic controller has some self-adaptive adjusting capability. It is combined with PI controller for the cascade control system and applied to superheated temperature control system of some 1900t/h once-through boiler. The comparison of this scheme with traditional cascade PID control and conventional FLC demonstrates the efficacy of this scheme.